Beam power tube



P 16, 1952 A. c. ROCKWOOD ET AL 2,611,098

BEAM POWER TUBE Filed June 27, 1950 l 60 0 a & M/VENTOAS 7a 68 7 66 ILAN 0. ROG/(W000 4 64 26 0 fiH/F/PY o. FZ'ZSENTf/AL 9 Patented Sept. 16,1952 BEAM POWER TUBE f Alan C. Rockwcod, Newton, Mass, and Harry IDFelsenthal, Camarillo, Calif assignors-to Ras theon ManufacturingCompany, Newton, Mass,

a corporation of Delaware,

Application June 27, 1950, Serial No. 170,528

1.3. laimsr.

This invention relates to beam. power tubes tron tube, the performanceof which depends upon the formation and controlof' one or more electronbeams. I

In beam power tubes the alignment of the grids is an importantfeaturefor proper opera tion. Forexample,v where a control grid and screen gridare used, the screen grid wires should be aligned'so that they fall inthe electron shadow of the control grid. wires. .By such alignment, thescreen grid wireswill not be in the direct path of the electron stream.The screen grid current is. thereby minimized and the outputcharacteristicsare generally improved.

Properly aligned condition ofthe control and screen grids ischaracterized by the appearance of a. symmetrical pattern formed by thegrid Windingswhich lends-itself to visual checking either with' thenaked eye or with the aid ofa microscope. 'At the timeof'checking;manual adjustments maybe made where found necessaryfor proper alignment.To insure such proper alignment, it is therefore important that duringassembly of the tube the full length of the control and-.: screen gridsbelvisible and accessible for adjustment until securely fixed inposition.

In addition tothe electrical poweroutput re quirements, there are manyapplications where physical structure with greater than normal abilityto'resist mechanical shock and vibration is. required. Itbecomes-difiicult to achieve such astructure which also-permits thedesirable full length inspection and alignment during assembly.Satisfying these requirements is further complicated-in tubes of.miniature-size..-and smaller. In suchsmall envelope tubes, spacerequirements prevent the use of conventional support rods protrudingfrom thetube base or button as-the rigid nucleus or starting point forassembly. Also,- because tubes of this size must'beproduced at low costfor commercial'reasons, a-relative1y simple structure adaptable to easyand rapid production line methods of assembly is essential.

Pursuant to the present invention, a structure has: been obtainedincorporating the above desirable features even in tubes-"of miniaturesize or smaller; This is achieved generally by using a: two -sectionanode rand combining one of the anode sections: with-the cathode andgridposie tioning spacers .to form at rigidijig-likerconstruction. Inthe present embodimenttwdfla'nged' half sections for the anodeiare used,One of the half sections is provided with projections. or tabs at itsupper'and lower ends. Theztabs of thishalf section are fitted intoreceiving slots for this purpose: in'the top" and bottom spacers.- Thetabs are then bent over therebyproviding a sub-assembly sufficientlyrigid to form the sup port and nucleus for. proper. fixing; alignmentand setting of: the: grids. After the grids have been aligned; thesecondhalf section of the. plate is :then set inplacewithits flanges:located on the flanges of the; first-mentioned half'oi the plate. Thesecond :half: of the -platexis alsopro' vided with. a projection or tabat each .of: its ends. These tabs fit into locating slots on theperiphery of the: spacers-thereby properly locat: ing the secondihalfofthe platewith respect to thefirstihalf. The side flanges-are then weldedtogether; ina finished rigid subassembly which, togetherrwiththesupportof the spacers against the; Wallof the envelopais capableofwwithstand-i ingrelatively high shock loading and abuse -;withoutmalfunctioning; I Properlylocated:recesses. in thesecond half of'qthe'plate: also provideafor final rough-checking of the alignment ofathegrids. These; recesses also insure .proper gas evacuation in:subsequent; rapid manufacturing operations in the =sealing;of theenvelope. Tolfurtlier increasectheprigidity of theassembly', metal :rodsmay be inserted: between the flanges of the plate half sections... By'making these rods sufficiently long to-extendrthrough holes for; thispurpose throughxboth the top; and bottom spacer and welding: the flangesintegrally with these rods, increased shock resistance of the structuremay be achieved. 1 To insure a low'order of grid plate'capacitance andparticularly to minimize the capacitiveefiect of .the anode tabsprotruding through the spacers, a novel arrangement for internalshielding-has been provided. The shield :vconsistsgenerally of acircularplate having a substantiallyrectangul'ar center. portion opening.The-four sides-of the rectangular portion are formed: downwardly todefine walls resting on the top spacer: These walls are'located'soithattogetheriwith the circular plate portion they isolate the protrudingplate-tabs from the protruding grid'rods which are located in therectangular center portion. The substantially rectangu'lariportion;hasdi -is agonal flanged corners.:' The flanges "protrude downwardly andarefiXedLas .by welding. to: proftruding tabs from beam confining plateswithin the above subassembly. The shield being held firmly in place inthis manner also provides support for a getter which is fixed to theplate portion as by welding. An opening across the entire circular plateand extending from the rectangular centerportion through the outside rimprovides an electrical discontinuity in the shield for minimizing eddycurrent formation.

In addition to suitable shielding at the bottom spacer, an interleadshield is used at the base of the tube and shields the grid stem leadfrom the plate stem lead. These and other advantages, features, andobjects of the invention will become more apparent from the followingdescription taken in connection with the accompanying drawings wherein:H

Fig. 1 is a cutaway isometric view with a half section of the anodeplate detached and shown separately for more clearly illustrating thegeneralsconstruction of the invention; j

Fig. 2 is. a'f-ra'gmentary. view of a typical control'gridand screengrid arrangement for illustrating proper alignment;

Fig.3 is a fragmentary'cross sectional view ofthe upper and lowersegments'of the embodimentin' Fig. il'take'n on line 33 of Fig. 4 formore clearly illustrating the. internal shielding and. other structuralfeatures oi. the invention; and 1 Fig. 4" is a view taken on line 4-4 ofFig. 3.

Referring first to Fig. 2, control grid support rods I andscreen'gridsupport rods I2, portions of which are shown in Fig. 2; holdthe control grid Iwires:I4.and screen grid wires 16, respectively, inposition .by grooves I8 suitably spaced on the support rods I0 and I2.The positionsof the control grid and.ScreenLgridJWiresLin Fig.2 areisho'wnflin; proper alignment. In the case of proper alignment as shownin Fig. 2, it is noted that the control grid wires I4 and screen gridwires I6 present a distinctive pattern wherein corresponding turns,though .nearly parallel, appear to intersect at the center line 20 whichcorresponds to the -axis of cathode44' (Figs. '3 and 4'). "Because ofthe distinctiveness of this pattern; the alignmeritof these grid wiresmay readily be checked visually. Thus if the con trol grid wires I'4 aretoo.hi'gh,"'the'point of interse'ction" with 'the' corresponding screengrid wires will appear to the'left of the center line 26 and more 01'each control grid wire I4 will be visible-above -the correspondingscreen grid wire I6 to the right of the point of intersection than isvisible below the screen grid wire i6 to the'left of the point ofintersection. When the control grid wires I4 are too low with respect tothe screen grid wires I6, the pattern will appear just opposite to thatexplained above. Alignment may usually be sec red by moving the controlgrid support rods H) or screen grid support rods I2 in thepronerdirection, up or down, with respect to eachother. I Since the grooves I8are evenly spaced and firmly hold the grid wires,suchcorre'ctive'movement may align all of the grid wires simultaneously.Such adjustment is more easily accomplished when the full length of thegrid windings is visible, since-it permits direct checking'of all turnsrather than depending upon uniformity pitch of the individual gridswhich would'benecessary if control of alignment were dependent upon asmall number of turns visible'througha small inspecticn'gap.

'It should be noted. that the screen grid wires 16 are' supported ingrooves 18 at a single point 4 on the support rods I2 and extendlaterally Ior some distance to clear the control grid wires I4 beforemaking an angular turn to then run in a plane parallel to that of thecontrol grid wires. This may be seen at 22 in Fig. 1. During manufactureand/0r subsequent handling before assembly, it often happens thatindividual turns of the screen grid wires I6 become bent near thesupport point of grooves I6 thereby varying the effective spacingbetween wires I4 and I6. As a result, these bent portions are notproperly aligned even after the support rods I0 and I2 are properlypositioned. These misaligned portionsmay be. discovered by visualinspection and maybe individually corrected manually as with a suitablestylus. Such adjustment of these individual portions provides not onlyfor improved operation of the tubes, but also for insuring that allsimilar tubes will have similar operating characteristics within closetolerances. In the present' invention, such corrective adjustmentis'insured by a construction which permits manual access to and visualinspection of the entire length of the grid coils during assembly. Thisconstruction at the same time is sufficiently rigid to withstandrelatively high shock loading.

Referring to Figs; 1' and 4, the anode consists of two circular halfsections 24 and 26 having flanges 28 and '30, respectively, extendinglaterally at the sides of each of the plate half sections. The flanges28 and 30 also have preferably circularly formed grooves 32 conformingto reinforcing rods 34 fitting between the respective flanges 28 and 30:The plate half section 24 also has at one end three projections or tabs36; 38 and 40 (Fig. 4). Similarly, it has three projection, tabs at itsother end, only one of which is visible in Fig. .3' at: 42; Duringassembly, cathode 44, control grid support rods I 0, screen grid supportrods I 2, projections or tabs 46 (Fig. 4) on both ends of beam confiningplates 48 and 50 (Fig. 1) and the above-mentioned projections or tabs onboth ends of the anode half section 24 are inserted in correspondingholes shaped to receive these elements in spacer plates 52 and 54 ofinsulating material such as mica. By bending tabs 36'and 40 of the platehalf section 24 which protrude through spacer plate 52, as shown in Fig.4, and by similarly bending similar 'tabs- (not shown) at the bottom endof the plate half section 24 protruding through the bottom spacer plate54, a rigid unitary sub-assembly is achieved. Since, at this stage ofassembly, the other half plate section 26 is not in position, it may beseen in Fig. 1 that the control and screen grid wires I4 and I6'arevisible on both sides of support rods I0 and I2 the full length of thegrid windings. The control grid support rods I0 and screen grid supportrods I2 may, at this point, be moved relative to each other to generallyalign the grid windings as explained above. While "the frictionalcontact between the spacer'plates 52 and 54 and the protruding gridsupport rods I0 and I2 is sufllcient to retain this alignment duringsubsequent assembly operations, it may be further insured by anchorstraps 53 and 55 "being fixed through opening 51 in the spacer plates 52and 54 and to the support-rods I 0 and I2, respectively, as by'welding.This sub-assembly may .then have attached thereto-an electrostaticshield 56 (Figs. 1 and 3) as by welding of the diagonal projections 58(Figs. 3 and) at the corners of a rectangular opening in shield 56 totabs 46 (Fig. 4) of the beam confining plates 48 and 50 proplates 48 andilflprotruding through the bottom spacer plate 54. I At this time also,'but-'r ton 62 containing suitable electrical stemi'leads,

and shield 64 for shieldinggrid stem lead 66 from plate stemlead 68 maybe electrically-at-v tached to the sub-assembly asby directly'weldingthe appropriate stem lead pins to'the desired point or by weldingconnectors Ill between the desired points as shown in: Fig. 3. As-thefinal step before insertion in' the envelope 12, the grid wires may bevisually checked and individually adjusted'as described aboveiandtheother plate half section 26 may be inserted in place and its flanges 3x0fixed to flanges 28 and reinforcing rods 34'; as: by welding. 'Aprojection or tab anda projection or tab 16 are. provided at each endof, the plate half section 26. 16 fit'into slots 18 and 80,respectively, in the top and bottom/spacers 52 and 54. This arrangementfacilitates rapid production line as sembly of. theplate half section26. to the plate half section 24, and also addsadditional rigiditytothe:assembledzstructure. Recesses 82 at the bottom of .the plate halfsection 26 provide both a rough means for checking of the final.alignment of the grids after assembly and also serve to insure properevacuationof the space vwithin the anode plateenclosure in the rapidsubsequent processing operations. i

.p The shield 56 above the .top spacer 52 has a rectangular openingortcenter portion with walls 84 .at each of its four sides. The walls 84on- .close the cathode 44 and projecting grid support rods I0 and I2,and,'to'gether withthe top plate-' like portion 86, electrostaticallyshield them from the plate tabs 36, 38 and 4B, and 14 andthe pro;truding portionsxo'f reinforcing rods 34. A slot or opening. 88 (Fig. 1)is provided through the fiat portion 86 of the shield 56 and. extendsthrough the rectangular-center wall portion 84 thereby creating anelectrical discontinuity, for

minimizing eddy current formations and reducnected to the cathode stemlead 92 (Fig. 1) and The tabs 14 and on the opposite sideof button 62 toan interlead 1 shield stem lead maintained at cathode potential; Thecapacitive effects of the interlead structure are thereby reducedandbecome an 'importantreduction under high frequency operation. Thisconstruction with its desirable low capacitances and eflicient poweroutput charac-' tached to said spacers-Landbeingi arranged to fasten to.said first section at said flanges, thereby permitting full lengthvisual inspectionandaligm ment of said grids during assembly oisaidgelece trontube. H 2. A beam power tube comprising'anenvelope, andan anode, a cathode, grids, and spacerspositioning said cathode andgrids in said envelope, said anode including a first and asecondsections having laterally extending flangesior fas teningsaidsections together, tabs at the .ex:

.tremities' of said first section fixed to said spacers, and meanspermitting attachmentof said second sectionto said first section afterassembly of said .grids and said first section in said spacers, therebypermitting full length visual inspectionand alignment of said :gridsbefore-assembly of said second section to said first sec- 3, A beampower tube comprising an envelope, and an anode, a cathode,beamconfining plates, grids, a top and a bottom spacer in said envelope,said spacers positioning saidcathode, beam ,confining plates and gridsand including openings for. tabs, said anode including a first and asecondl sections having laterally extending ufianges, tabs at theextremities of said first sectionjthe tabs at. one extremity of saidfirst sectionflxed incorresponding openings in said topspacer the tabsof the other extremity of said first section fixed in correspondingopenings in said bottom spacer, a tab at ea'chextremity of said secondsection located in corresponding recesses of said top and bottomspacers, said recesses extending :to the edges of said spacers, meansfastening said second sectionto said first section at said-flanges,thereby permitting full length visual inspection andralignment of saidgrids during assembly of said'tube; x i z 4. For a beam poweritube,spacer plates, a curved anode structure between, said spacer plates,said anode. structure including two half sections having flangesextending laterally therefrom, projections at the extremities of a firstof said half sections, said projections being injrigid engagement withsaid spacer plates, projections at the extremities of asecondof' saidhalf sections, said, last-mentioned. projections being in locatingengagement with said spacer "plates, thereby permitting, full lengthvisual inspection and alignment'of grids within'said anode structureduring assembly of saidtube. I 5. Fora beam .power tube, top and bottomspacer plates, a curved anode structure between said spacer lates, saidanode structure including two half sections having flanges extendinglaterally therefrom, projections at the extremities of a first of saidhalfsections, openings in said spacer plates conforming to thecross-secs tion of said projections receiving saidprojections andproviding rigid engagement, between said first half section and saidspacers, projections at the extremities of a second of said half.sections, recesses in said spacer plates adapted to position saidsecond half section with respect to said first half section, saidrecesses extending to the edges of said spacers, thereby permitting fulllength visual inspection and alignment of grids within said anodestructure during assembly of said electron tube.

6. For a beam power tube a shield comprising a fiat plate section, asubstantially rectangular recess formed at the center of said fiat platesection, said rectangular recess defining four side walls extendingdownwardly from said plate section, projections. extending downwardlyatthe corners or said rectangular recess for. providing support andelectrical connectionwith beam. confining plates in said. tube, and anopening from said rectangular recess through said flat plate section forproviding electrical discontinuity in said shield,

For a. beam power tube, a shield comprising a. circular flat platesection, a. substantially rectangular recess. formed at the center ofsaid fiat plate section, said rectangular recess defining four sidewalls extending downwardly from.v said plate section, and projections,extending downwardly at the corners of said rectangular recess forproviding support and electrical connection with beam confining platesinsaid tube.

8. An anode. structure comprisin a first and a. second curved plate.sections surrounding a cathode and grid structure, flanges at the sidesof; saidplate sections for fastening said sections together, projectionsat the upper and lower. ends of said first section, disks of insulatingmaterial for-positioning said cathode and grid structure and havingorifices for receiving said projections,

said positioning disks being fixed to the. upper and lower ends of saidplate section by said projections, projections at the upper and lowerends of. said second plate section, and slots extending in'from' theedges of said positioning disks for receiving said projections of saidsecond plate .section and locating said second plate section withrespect to said. first plate section.

9. Inv a beam power tube, an envelope, and an anode, a cathode, beamconfining plates, grids and electrostatic. shielding in said envelope,said anode. including afirst and a second curved plate sections forsurrounding said cathode and grids and beam confining plates, flanges atthe sides of said plate sections fastening said sections together,projections at the upper and lower ends of said first section, disks ofinsulating material for positioning said cathode, grids. and beamconfining plates and having orifices for receiving said projections,said positioning disks being fixed to the upper and lower ends of saidfirst plate. section by said projections, projections at the upper andlower ends of said second plate section, and recesses in saidpositioning disks for .receiving said projections of said second platesection and locating said second plate section with respect to saidfirst plate section.

10. In a beam power tube of the type having an anode, a cathode, beamconfining plates, grids, and spacer plates pierced by projections ofsaid anode, cathode, beam confining plates and grids, an electrostaticshield between said anode 4 projections and said grid and cathodeprojections including a fiat plate section above said anode projections,a substantially rectangular opening in said fiat plate section definingfour side walls extending downwardly from said plate section and betweensaid plate projections and said cathode and grid projections, andprojections extending downwardly afhthe: corners of saidrectangularrecess for providin support and 5111215.? ing connection with said beamdeflecting plate projections; in said. tube, and an opening from saidrectangular recess through said flat plate section for providingelectrical discontinuity in said shield.

11,.In a beam power tube of the type having an anode, a.cathode, beamconfining plates, grids, and spacer plates pierced by projections ofsaid anode, cathode, beam confining plates and grids, an electrostaticshield between said anode projections and said grid and cathodeprojections, said shield having a split construction for providingelectrical discontinuity thereby minimizingv eddy current formations insaid shield.

12. A beam power tube comprising an envelope, and, an anode, a cathode,grids, and spacers positioning.- said cathode and grids. said anodeincluding a first and. a second .fianged sections and reinforcing rodsegments between the flanges of said sections, said first section havingprojections at its ends fastened to said spacers, said second sectionbeing arranged to fasten to said firstsection andv said rods at saidflanges, thereby providing a rigid construction permitting full lengthvisual inspection and alignment of said grids during assembly of saidelectron tube.

13.. For a beam power tube, a shield for providing electrostaticshielding. between anode projections and grid and cathode projections insaid tube, said shield comprising a fiat plate section, and an openingformed at substantially the center of said fiat plate section, theperimeter of said opening defining side walls extending downwardly fromsaid fiat plate section for positioning between said anode projectionsand said cathode and grid projections and for providing electricalconnection with beam confining plates in said tube.

ALAN C. ROCKWOOD. HARRY D. FELSENTHAL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS,

Number Name Date 2,250,184 Miller July 22, 1941 2,355,083 Krim Aug. 8,1944 2,433,410 Walker et' a1 Dec. 30,1947 2,459,861 Wood Jan. 25, 19492,464,241 Krim Mar. 15, 1949 2,464,272v Suesholtz et al Mar. 15, 19492,465,385 Marsh-ct al. Mar. 29, 1949 2,476,646 Warren et al July 19,1949 2,476,940 Wood July 19, 1949 2,486,829 Ewing Nov. 1, 1949 2,487,592Rishell Nov. 8, 1949 2,490,177 Van der Berge et a1. Dec. 6, 19492,493,555 Simpson Jan. 3, 1950

